the minWidth config appears to be getting overwritten somewhere between initComponent and doAutoWidth. I have poked around and haven't been able to track down where exactly, but by the time doAutoWidth is called minWidth is already set back to the default 75.

in 2.x
http://content.screencast.com/users/VinylFox/folders/Jing/media/aede85ec-4753-4ec2-aef8-971ee0abe991/2009-04-08_0859.png